It is well known that electromagnetic radio frequency emissions are generated by the ignition wires during normal operation of an engine. It is also well known that by sampling the electromagnetic emissions, ignition information can be obtained for evaluating the operation of the engine. Prior art devices are either triggered by the electromagnetic emissions or measure the amplitude of the emissions to provide spark information. These prior art devices measure the electromagnetic emissions at the spark plug wire or boot, but are not capable of determining whether a spark occurred at the end of the spark plug.
Some prior art testing devices include wire antennas that are bent in shapes and encased in housings. Due to their use of encased bent wires, they are typically more expensive and difficult to manufacture consistently. In addition, it is more difficult to consistently produce high quality prior art testing devices employing encased bent wires due to the inherent process variances associated with manufacturing such encased bent wire devices.